U.S. patent number 4,614,097 [Application Number 06/824,304] was granted by the patent office on 1986-09-30 for internal locking mechanism for barrel type locks.
Invention is credited to John A. Signorelli.
United States Patent |
4,614,097 |
Signorelli |
September 30, 1986 |
Internal locking mechanism for barrel type locks
Abstract
A plunger type lock comprising a barrel with an axial bore,
locking members in the form of balls housed in the barrel wall and
extensible outwardly from the barrel by a plunger axially slidable
within the barrel bore, at least one further ball housed in an
opening in the wall of the plunger and extensible outwardly
therefrom and a peripheral groove on the inner wall surface of the
barrel for receiving the further ball, the further ball being
forceably moved and held in the barrel's groove by an incorrect
key, instrument or an implement to prevent and resist movement of
the plunger whenever an unauthorized attempt to operate and open
the lock is made.
Inventors: |
Signorelli; John A. (Brooklyn,
NY) |
Family
ID: |
27060023 |
Appl.
No.: |
06/824,304 |
Filed: |
January 30, 1986 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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519999 |
Aug 3, 1983 |
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232137 |
Apr 27, 1981 |
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Current U.S.
Class: |
70/34; 70/386;
70/395 |
Current CPC
Class: |
E05B
67/365 (20130101); Y10T 70/7751 (20150401); Y10T
70/443 (20150401); Y10T 70/7802 (20150401) |
Current International
Class: |
E05B
67/00 (20060101); E05B 67/36 (20060101); E05B
067/36 () |
Field of
Search: |
;70/23,32-34,386,395,397-398,402-404 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Wolfe; Robert L.
Attorney, Agent or Firm: Brooks Haidt Haffner &
Delahunty
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATION
This application is a continuation-in-part of application Ser. No.
519,999, filed Aug. 3, 1983 and now abandoned which was a
continuation-in-part of U.S. Ser. No. 232,137 filed Apr. 27, 1981
and now abandoned.
Claims
What is claimed is:
1. A plunger type lock comprising a barrel with an axial bore,
locking members on said barrel and extensible outwardly from said
barrel, plunger means movable axially within said bore and in a
first axial, locking position thereof, holding the locking members
in extended position, said plunger means in a second axial,
unlocking position permitting the locking members to move inwardly
of said barrel, means biassing said plunger means into its first
axial position, and means for preventing axial movement of said
plunger means into its second axial position comprising at least
one further locking member carried by said plunger means and
movable inwardly and outwardly of said plunger means, said barrel
having stop means engageable with said further locking member when
said plunger means is in its first axial position and said further
locking member extends outwardly of said plunger means, whereby
displacement of said further locking member outwardly of said
plunger means with an implement when said plunger means is in its
locking position causes said further locking member to engage said
stop means and prevents axial movement of said plunger means toward
its second axial position.
2. A lock as set forth in claim 1 wherein said barrel has an
opening therein at one end thereof for the entrance of expansible
key means into the bore of said barrel, wherein said plunger means
has a socket therein which opens toward said end of said barrel,
said socket having a first wall surface portion engageable by said
key means to cause said plunger means to move into its second axial
position as the key means is retracted from said bore, and wherein
said further locking member is located at a second portion of the
wall surface of said socket which is farther from said end of said
barrel than said first portion of the wall surface.
3. A lock as set forth in claim 1 wherein said barrel has an
opening therein at one end thereof for the entrance of expansible
key means into the bore of said barrel, wherein said plunger means
has a socket therein which opens toward said end of said barrel,
said socket having a first wall surface portion engageable by said
key means to cause said plunger means to move into its second axial
position as the key means is retracted from said bore, and wherein
said further locking member is located at a second portion of the
wall surface of said socket which is closer to the end of said
barrel than said first portion of the wall surface.
4. A lock as set forth in claim 2 or 3 wherein said further locking
member is a ball located in and movable in a passageway in said
plunger means which extends from said socket to the outer periphery
of said plunger means and wherein said stop means is a groove in
the interior wall of said barrel which extends around the axis of
said bore and which receives a portion of said ball when it extends
outwardly of said plunger means.
5. A lock as set forth in claim 4 wherein said ball has a diameter
greater than the radial thickness of the wall of said socket
adjacent thereto but not greater than the radius of the outer
surface of said wall.
6. A lock as set forth in claim 4 wherein said passageway has
dimensions which permit said ball to extend into said socket but
which prevent said ball from falling into said socket.
7. A lock as set forth in claim 4 wherein the diameter of said
passageway at said socket is less than the diameter of said
ball.
8. A lock as set forth in claims 1, 2, 3 or 4 wherein said plunger
means has two parts, one of said parts carrying said further
locking member and having an axial bore and the other of said parts
being a piston with a shaft within the bore of said one part and
being axially movable with respect to said one part, said other
part being biassed by spring means toward said one part and said
piston holding said first-mentioned locking members extended when
said one part is moved axially without maintaining said piston in
the position thereof when said plunger means is in its first axial
position.
9. A lock as set forth in claim 8 wherein one end of the axial bore
of said one part is adjacent said further locking member and
wherein, in the first axial position of said plunger means, the end
of said shaft remote from said piston is at said one end of the
axial bore of said one part to prevent insertion of an implement in
the axial bore of said one part when it is in its first axial
position.
10. A lock as set forth in claim 4 wherein said plunger means has
two parts, one of said parts having said passageway in which said
ball is disposed and having an axial bore and the other of said
parts being a piston with a shaft within the bore of said one part
and being axially movable with respect to said one part, said other
part being biassed by a spring means toward said one part and said
piston holding said locking members extended when said one part is
moved axially without maintaining said piston in the position
thereof when said plunger means is in its first axial position and
wherein the diameter of said ball is less than the radius of the
outer surface of said one part whereby said piston is in its first
axial position by a rod extending into the bore of said one part
and engaging the end of said shaft without moving said ball
outwardly of said one part.
11. A lock as set forth in claim 1 wherein said barrel has an
opening therein at one end thereof for the entrance of key means
into the bore of said barrel, wherein said plunger means has pin
means thereon which is movable axially of said plunger means and
part of which extends from said plunger means and part of which
extends from said plunger means toward said end of said barrel,
said pin means being engageable by said key means to cause said
plunger means to move into its second axial position as the key
means is retracted from said bore, and wherein said further locking
member is located at a portion of said plunger means which is
farther from said end of said barrel than at least a portion of
said part of said pin means.
12. A lock as set forth in claim 1 wherein said barrel has an
opening therein at one end thereof for the entrance of key means
into the bore of said barrel, wherein said plunger means has pin
means thereon which is movable axially of said plunger means and
part of which extends from said plunger means toward said end of
said barrel, said pin means being engageable by said key means to
cause said plunger means to move into its second axial position as
the key means is retracted from said bore, and wherein said further
locking member is located at a portion of said plunger means which
is closer to said end of said barrel than said part of said pin
means.
13. A lock as set forth in claim 11 wherein said plunger means has
a wall extending around at least a portion of said part of said pin
means with its inner surface spaced from the latter and wherein
said further locking member is located in said wall.
14. A lock as set forth in claim 11 wherein said plunger means has
a bore into which said pin means extends, wherein said further
locking member is located in the wall of said first-mentioned bore
and wherein said pin means has a portion which is engageable with
said further locking member when said pin means is moved in the
direction away from said end of said barrel for engaging said
locking member with said stop means.
15. A lock as set forth in claim 14 wherein said further locking
member is a ball located in and movable in a passageway in the wall
of said bore of said plunger means, wherein said pin means has a
peripheral groove in the portion thereof which is within said bore
of said plunger means for receiving a portion of said ball when
said pin is in its position nearest said one end of said barrel and
wherein said stop means is a groove in the interior wall of said
barrel which extends around the axis of said bore of said barrel
and which receives a portion of said ball when it extends outwardly
of said plunger means and further comprising spring means biassing
said pin means into said position thereof.
16. A lock as set forth in claim 11 or 12 wherein said further
locking member is a ball located in and movable in a passageway in
said plunger means and said stop means is a groove in the interior
wall of said barrel which extends around the axis of said bore of
said barrel which receives a portion of said ball when it extends
outwardly of said plunger means.
17. In a key, for use with a barrel type lock, having a central
rod-like element, an elongated tubular sleeve concentric with and
slidable along said rod-like element, said tubular sleeve having an
enlarged end, a plurality of relatively flexible fingers positioned
radially outward of said sleeve, means for moving said enlarged end
between the rod-like element and the fingers to force said fingers
radially away from said rod-like member, the improvement comprising
one or more peripheral grooves in and around a finger or fingers of
the key to cooperate with radially movable locking means of the
barrel type lock.
18. A grabber-type key for use with a barrel lock of the type
having an internal plunger, having means to grip a pin associated
with said plunger, the improvement comprising one or more
peripheral grooves in and around the key to cooperate with radially
movable locking means of said plunger of the barrel lock.
19. A key for a plunger type lock of the type which engages a
plunger of such a lock by expansion of an end of the key, including
one or more peripheral grooves formed in the key at or near an
expanding end of the key for cooperating with radially movable
internal locking means of said plunger of the lock.
20. The key of claim 17 including a radially extending projection
at a free end of each said relatively flexible finger for
engagement with mating means of said barrel lock.
21. The lock of claim 2 wherein said socket has a wall which is
tapered outwardly toward said end of said barrel.
22. The lock of claim 1 wherein said plunger means has a socket
therein which opens toward said end of said barrel, said socket
having a portion which tapers outwardly toward said opening and a
cylindrical wall portion which is further from said socket opening
for engagement by said key means.
23. The lock of claim 22 wherein said at least one further locking
member is located at said cylindrical wall portion.
24. The lock of claim 1 wherein there are three of said further
locking members arranged at equally arcuate spaces around said
plunger means.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to plunger type locks and particularly to
locks which have an operating mechanism which is unlocked when a
key is inserted axially into the lock to the proper depth and then
partially withdrawn.
2. Description of the Prior Art
Plunger type locks are disclosed in U.S. Pat. Nos. 3,002,368;
3,714,802; 3,033,016; 3,478,548; 3,835,674; 4,015,456; 4,040,279;
4,058,992 and 4,155,232 and are relatively widely used to prevent
tampering with gas, water and electric meters, unauthorized
operation of valves and switches, etc. In general, such locks have
a hollow barrel containing a plunger axially movable in the barrel
from a locking position to an unlocking position, the plunger being
spring biassed into the locking position. One end of the barrel is
receivable in a cap or housing having a recess or groove. In the
locking position of the plunger, a plurality of locking members, in
the form of steel balls are held by the plunger, partly extending
outwardly of the barrel and received in the recess of the cap or
housing so that the barrel cannot not be removed from the cap or
housing.
To unlock the lock of some prior art constructions, and thereby to
permit separation of the barrel from the cap or housing, a key with
spreadable fingers at its end is inserted into an opening in one
end of the barrel and is moved lengthwise or axially of the barrel
until the fingers are received within a socket at the end of the
plunger, at which time, the fingers are spread apart causing them
to engage the wall of the socket in the plunger. Thereafter, as the
key is moved axially in a direction opposite to the key insertion
direction, the plunger moves axially of the barrel permitting the
steel balls to move inwardly of the barrel and out of the recess in
the cap or housing.
In other types of plunger type locks, e.g. those disclosed in U.S.
Pat. Nos. 3,478,548; 4,015,456 and 4,058,992, the operation is
similar except for the use of a "grabber" type key to grab or grip
a pin associated with the plunger rather than a key with spreadable
fingers for engaging the wall of a socket in the plunger.
It is known in the lock art that persons seeking unauthorized
access to utility meters, gas shut-off valves, current transformer
cabinets, switches, etc., are resourceful and adopt ingenious ways
to open the locks used. As a consequence, considerable effort has
been devoted to the development of economical and sturdy locks for
locking such devices which are resistant to opening thereof by
unauthorized means. One type of expedient used by unauthorized
persons is a nail, rod, tubing or improvised tool inserted into the
lock in such a manner as to engage the wall of the plunger socket
upon retraction of such nail, rod, tubing or tool in the same way
that it is moved by a correct key. Another expedient is to obtain
unauthorized access to an incorrect key and to manipulate such
incorrect key in a way which will cause unlocking movement of the
plunger.
One object of the invention is to provide a plunger type lock in
which the plunger is locked in its locking position whenever an
attempt is made to pick the lock with an implement which can be
inserted into the lock farther than an authorized key can be
inserted therein and/or whenever a key or implement not having the
correct keying positions of an authorized key is used.
Another object of the invention is to make locks of the type which
are operable by a "grabber" type key more resistant to picking by
an improper key or an implement other than a key by locking the
plunger in its locking position whenever an attempt is made to pick
the lock with such a key or implement.
SUMMARY OF THE INVENTION
In one preferred embodiment of the invention, the plungers of known
types of plunger locks are modified to include one or more further
locking member or members in the form of a steel ball or balls at a
portion of the key receiving socket which is farther from the key
receiving end of the lock than the surface of the wall of such
socket which is normally engaged by correct, authorized key. Such
ball or balls co-operate with a recess or groove at the interior
wall of the barrel in such a manner that when an implement other
than a correct key is inserted in the lock, the ball or balls enter
the recess in the barrel and prevent axial movement of the plunger,
thereby not allowing the conventional locking balls to be received
by the barrel and thus maintain the locking mode.
In modified embodiments of the invention in which the positions of
the conventional locking balls of the lock are determined by the
position of a movable pin which is grippable by a "grabber" key,
the further locking member or members of the preferred embodiment
are either positioned by the movable pin whereby displacement of
the pin by an incorrect implement will prevent release of the
conventional locking balls or positioned by an implement other than
a correct key so as to prevent release of the conventional locking
balls.
Other objects and advantages of the present invention will be
apparent from the following detailed description of the presently
preferred embodiments thereof, which description should be
considered in conjunction with the accompanying drawings in
which:
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is an axial, cross-sectional view of the plunger type lock
shown in U.S. Pat. No. 3,714,802 modified to incorporate the
invention;
FIG. 2 is a cross-sectional view taken along the line 2--2
indicated in FIG. 1;
FIG. 3 is a fragmentary, cross-sectional view similar to FIG. 1 but
showing the effect of inserting a tube or rod, rather than the
proper key, into the lock shown in FIG. 1;
FIGS. 3A, 3B and 3C show different ways of positioning one or more
sets of locking balls for use with a key having one or more
circumferential grooves.
FIG. 4 is an axial, cross-sectional view of the plunger type lock
shown in U.S. Pat. No. 4,040,279 modified to incorporate the
invention;
FIG. 5 is similar to FIG. 4 but shows the positions of the parts
when the lock is unlocked;
FIGS. 6 and 7 are axial, cross-sectional views of the plunger type
lock shown in U.S. Pat. No. 4,015,456 modified in a first way to
incorporate the invention; and
FIGS. 6A and 7A show modified versions of the mechanisms of FIGS. 6
and 7 which employ additional locking balls;
FIGS. 8 and 9 are axial, cross-sectional views of the plunger type
lock shown in U.S. Pat. No. 4,015,456 modified in a second way to
incorporate the invention.
FIG. 10 is a detail view in cross-section showing means for
retaining a locking ball.
FIG. 11 is a detail view in section of a socket having a tapered
wall in accordance with the invention.
FIG. 12 is a view in section similar to that of FIG. 2, but showing
three locking balls equally radially spaced about a socket.
FIG. 13 shows another form of socket having a tapered wall.
FIG. 14 is a detail view of the socket-engaging end of a key
adapted for use in conjunction with a socket of the type shown in
FIG. 13.
DESCRIPTION OF PREFERRED EMBODIMENTS
Except for the modifications required for the purpose of the
invention, the lock 1 illustrated in FIGS. 1-3 is the same as the
lock illustrated in U.S. Pat. No. 3,714,802 and only a brief
description of the latter lock will be included herein. Thus, the
lock 1 includes a tubular barrel 2 closed at one end which passes
through openings in the parts 3 and 4 to be locked relative to each
other. A plunger 5 is slidably mounted, for axial movement, within
the barrel 2 and has a socket 6 at one end from which the sleeve 33
of U.S. Pat. No. 3,714,802 has been removed. The end portion 7 of
the plunger 5 maintains the locking members 8 and 9, in the form of
steel balls, in a peripherally extending groove 10, in a cap 11
when the lock is locked thereby preventing separation of the cap 11
and the barrel 2.
The plunger 5 is urged toward the locking position thereof by a
spring 12 acting between an end of the plunger 5 and a further cap
13 secured to the barrel 2, such as by reason of a press fit
therebetween. As described in U.S. Pat. No. 3,714,802, the lock 1
may be unlocked by means of a key which has an expandable end and
which is of the proper length, the key being inserted into the
barrel 2 by way of the keyhole 14 and the expandable end thereof
engaging the wall portion 15 of the socket 6. When the key is so
inserted and the end thereof is expanded, the key is then partially
withdrawn from the barrel 2 causing the plunger 5 to move to the
right, as viewed in FIG. 1, which permits the locking members 8 and
9 to move inwardly of the barrel 2 and out of the groove 10 and
permits removal of the cap 11 from the barrel 2.
In accordance with the invention, a further peripheral groove 16 is
provided on the inner wall of the barrel 2 and one or more further
locking members, such as steel balls 17 and 18, are mounted in
passageways 19 and 20 (FIG. 2) in the barrel 2 at a distance from
the outer end 13a of the cap 13 and greater than the distance of
the wall portion 15 from the outer end of the cap. The passageways
19 and 20 extend from the interior of the socket 6 to the exterior
of the plunger 5 and permit portions of the balls 17 and 18 to
enter into the groove 16. The inner ends of the passageways 19 and
20 are shaped and have dimensions, e.g. a diameter less than the
diameter of the balls 17 and 18, to prevent the balls 17 and 18
from falling into the socket 6. However, the inner ends of the
passageways 19 and 20 are dimensioned so as to allow a portion,
preferably one-quarter of the ball sphere, to extend into the
socket 6. Also, the diameters of the balls 17 and 18 are larger
than the thickness of the walls of the socket 6 where the balls 17
and 18 are located, but preferably the diameters of the balls 17
and 18 are such that there is at least a small spacing therebetween
when they are at their radially innermost positions.
Usually, the expandable key used to open the lock 1 has an abutment
thereon which abuts the outermost end 13a of the cap 13 when the
expandable end of the key is in the position in which it can engage
the wall portion 15. Therefore, a correct key can unlock the lock 1
without moving the balls 17 and 18 into the groove 16. However, if
an incorrect key having a greater spacing between such abutment and
the expandable end is inserted into the barrel 2 until the abutment
thereon abuts the end 13a, the expandable end thereof will move the
balls 17 and 18 radially outwardly into the groove 16, and when an
attempt is then made to retract the incorrect key, the plunger 5 is
prevented from moving by reason of the engagement of the balls 17
and 18 with the wall of the groove 16.
Similarly, when an implement 21, such as a rod or tube which has a
diameter large enough to frictionally engage the wall portion 15,
is driven into the barrel 2 through the keyhole 14 and beyond the
side of the wall portion 15 remote from the end 13a, as illustrated
in FIG. 3, in an attempt to unlock the lock 1, the implement 21
will similarly move a portion of the balls 17 and 18 into the
groove 16 and prevent axial movement of the plunger 5 and release
of the balls 8 and 9.
Although two balls 17 and 18 have been shown in FIGS. 1-3 and will
be shown in the figures described hereinafter, it will be apparent
that only one ball, 17 or 18, or more than two balls 17 and 18 may
be used.
FIGS. 4 and 5 illustrate the use of the invention in connection
with a plunger type lock of the type illustrated and described in
U.S. Pat. No. 4,040,279 and reference is made to the latter patent
for a complete description of the lock parts and operation thereof
other than the parts added thereto for the purpose of the
invention. Only a brief description of the lock parts and operation
will be set forth herein.
FIG. 5 illustrates the lock 22 in its locked condition with a
protective pin 23 therein, and FIG. 5 illustrates the lock 22 in
its unlocked condition. The lock 22 has a barrel 24 with a cap 25
secured to one end thereof, for example, by frictional fit and a
cap or housing 26 at the other end thereof. A plunger 27 is axially
slidable within the barrel 24 and is urged into its locking
position by a spring 28 acting between one end of the plunger 27
and the cap 25. In its locking position, a portion 29 of the
plunger 27 holds the locking members 39 and 31, in the form of
steel balls, in a peripheral groove 32 (FIG. 5) in the cap 26 so
that the cap 26 cannot be separated from the barrel 24. When the
plunger 27 is retracted by a key 33, as shown in FIG. 5, the balls
30 and 31 are permitted to move inwardly of the barrel 24, and the
cap 26 may be separated from the barrel 24. Parts of a frangible
member included for the purposes described in said U.S. Pat. No.
4,040,279 are designated by the reference numerals 34, 35 and 36,
and the piston described in said last-mentioned patent is
designated by the reference numeral 37.
The plunger has a socket 38 at the end thereof nearest the cap 25,
and the socket 38 has a wall portion 39 which is engageable by the
expandable fingers 40 of the key 33 for the purpose of moving the
plunger 27 axially and thereby, releasing the balls 30 and 31 and
unlocking the lock 22.
For the purposes of the invention, a further pair of locking
members, in the form of steel balls 41 and 42, are received in
passageways 43 and 44 in the wall of the barrel 27. The passageways
43 and 44 have the shape and dimensions described in connection
with the passageways 19 and 20 shown in FIGS. 1-3, and the balls 41
and 42 have the dimensions described in connection with the balls 8
and 9 shown in FIGS. 1-3. When the plunger 27 is in its locking
position and the balls 41 and 42 are moved outwardly of the barrel
24, portions of the balls 41 and 42 are received in a peripheral
groove 45 in the inner wall of the barrel 24. On the other hand, if
the wall portion 39 is engaged by the expandable fingers 40 of a
correct key 33, the balls 41 and 42 are free to move inwardly and
do not impede axial movement of the plunger 27.
Accordingly, as described in connection with FIGS. 1-3, an
implement or incorrect key which is inserted into the barrel 24 far
enough to displace the balls 41 and 42 outwardly of the plunger 27
cannot move the plunger 27 because of the entry of the balls 41 and
42 into the groove 45. However, a correct key 33 can engage the
wall portion 39 of the socket 38 without displacing the balls 41
and 42 outwardly of the plunger 27 and can move the plunger 27 to
unlock the lock 22.
FIGS. 3A, 3B and 3C show modifications of the mechanism of FIG. 3
utilizing locking members which are not located near the bottom, or
closed end, of the socket 6 of the plunger 5. This modification
permits for greater variety in the combinations of lock and key
which can, for example, be provided to different users, so that one
user's key will not open another user's lock.
The mechanism of FIG. 3A has locking balls 17a and 18a which are
similar to the balls 17 and 18 of FIG. 3, but which are mounted to
move radially in and out of passageways 19a and 20a, which
passageways are spaced away from the bottom of the socket 6. FIG.
3A shows in simplified form, an authorized key K1 in position to
open the lock. The key K1 would be a key having an expandable end
as described in U.S. Pat. No. 3,714,802 with fingers that spread
outward to engage the wall of the socket 6, but for simplicity the
finger details are omitted. The key K1 (actually the fingers at the
end of the key) receives the locking balls 17a and 18a in the
arcuate recess G which is opposed to the passageways 19a and 20a
when the key K1 is in position to open the lock, i.e. inserted
fully into the socket 6 as shown. An unauthorized key, such as the
implement 21 shown in FIG. 3, or even a key having spreadable
fingers but no recess G, or with a recess located at a different
location with respect to the distal end of the key, would push the
locking balls 17a and 18a outward into groove 16a and prevent the
axial movement of the plunger necessary to unlock the lock.
The lock of FIG. 3B has locking balls 17a and 18a like those shown
in FIG. 3A, as well as additional locking balls 17b and 18b. To
accomodate these additional locking balls 17b and 18b the socket 6
may be somewhat deeper or longer as shown in FIG. 3B. The key K2
illustrated in FIG. 3B has arcuate recesses G2 and G3, and would
open the lock of FIG. 3B if those grooves G2 and G3 were properly
located along the length of the key K2 when spreadable fingers (not
shown) of the key K2 were spread apart to engage the walls of the
socket 6. However, the key K2 shown in FIG. 3B has its second
groove or recess G3 located too close to the recess G2 to receive
the second set of locking balls 17b and 18b, so it cannot open the
lock of FIG. 3B. If the second recess G3 were properly positioned
opposite the passageways 19b and 20b when the key K2 was fully
inserted into the socket 6, it would function to open the lock.
FIG. 3C illustrates a similar result with a plunger 5 having three
sets of locking balls, 17a and 18a, 17b and 18b and 17c and 18c,
located at spaced positions along the length of the socket 6 for a
locking fit within grooves 16a, 16b and 16c when an implement which
lacks recesses to receive all of the locking balls is inserted into
the socket. A proper key to unlock the mechanism of FIG. 3B would
be dimensioned so as not to push any of the locking balls outward
into the grooves 16a-16c. The correct key must thus be of the
proper length and also have recesses correctly spaced. As indicated
with respect to FIG. 3 the proper key would abut against the end
surface 13a to prevent insertion so deep as to displace the
innermost locking balls 17a and 18a outwardly.
FIGS. 6-9 illustrate modified forms of the plunger type lock
requiring a "grabber" key which is shown in U.S. Pat. No.
4,015,456. FIGS. 6 and 7 illustrate one way in which such lock may
be modified to incorporate the invention, and FIGS. 8 and 9
illustrate another way in which such lock may be modified to
incorporate the invention. While not essential, such lock may be
modified to include both of the modifications disclosed in FIGS. 6
and 7 and in FIGS. 8 and 9.
The lock parts common to the lock of the invention and to the lock
shown in said U.S. Pat. No. 4,015,456, and their functions and
operation, are described in detail in said patent and will be
described only briefly herein.
The locks 46 and 46a shown in FIGS. 6-9 comprise a barrel 47 with
an enlarged head 48 having a keyhold 49. A cap 50 is held on the
barrel 47, when the lock is locked, by steel balls 51 and 52 held
in a peripheral groove 53 in the inner wall of the cap 50, as
described hereinafter, such cap 50 corresponding to the caps 11 and
26 described hereinbefore. Lock 46 has a plunger 54 which is
axially slidable within the barrel 47 and which is a modified form
of the plunger shown in U.S. Pat. No. 4,015,456 but which performs
the functions described in the patent. The plunger 54 is biassed
into its locking position by a spring 55 and has a portion 54a
which maintains the balls 51 and 52 in the groove 53 when the
plunger 54 is in its locking position. The plunger 54 has a pin 56
and a spring 57 therein, the pin 56 being movable axially of the
plunger 54.
The plunger 54 has a pair of passageways 58 and 59 therein for
loosely receiving a pair of locking members in the form of steel
balls 60 and 61 and the barrel 47 has a peripheral groove 62 for
receiving the balls 60 and 61. The passageways 58 and 59 are shaped
and dimensioned and the balls 60 and 61 are dimensioned as
described hereinbefore in connection with the passageways 19 and 20
and the balls 17 and 18 respectively.
When a correct key 63 is inserted into the lock 46 as shown in FIG.
6, the end of the key 63 can grab the pin 56 without interfering
with radially inward movement of the balls 60 and 61, and
therefore, the key 63 may be retracted after the end thereof grabs
the pin 56 causing the plunger 54 to move to the right, as viewed
in FIG. 6, and thereby moving the portion 54a to a position such
that the balls 51 and 52 can move inwardly out of the groove 53.
When the balls 51 and 52 move out of the groove 53, the cap 50 may
be removed from the barrel 47.
Key 63 has an abutment 63a thereon which engages the key receiving
end of the barrel 47 when the key 63 is fully inserted, and the
spacing between the abutment and the fingers 63b of a correct key
63 is such that the fingers 63b do not interfere with inward
movement of the balls 60 and 61. After the key 63 is inserted to
its full depth and the fingers 63b are around the pin 56, the
fingers 63b are retracted while the outer tube and the abutment 63a
of the key 63 are held stationary which causes the fingers 63b to
grab or grip the pin 56. After the fingers 63b grip the pin 56, the
entire key 63 is moved to the right, as viewed in FIG. 6, to move
the plunger 54 and thereby release the balls 51 and 52.
FIG. 7 illustrates the insertion into the lock 46 of an incorrect
key 64 having a spacing between the abutment 64a and the finger 64b
which is greater than the corresponding spacing between the
abutment 63a and the fingers 63b. FIG. 7 illustrates the position
of the finger 64b after they have been retracted so as to grip the
pin 56 and before an attempt is made to move the entire key 64 to
the right. It will be observed that in this position, the fingers
64b prevent movement of the balls 60 and 61 completely out of the
groove 62, and therefore, when an attempt is made to move the
entire key 64 to the right, movement of the key 64, and hence, the
plunger 54, is prevented by reason of engagement of the balls 60
and 61 with the wall of the groove 62. In this way, release of the
balls 51 and 52, and unlocking of the lock 46 with an incorrect key
is prevented.
Similar results would be obtained if a rigid tube is driven into
the lock 46 in place of the key 64. Thus, if the tube has an outer
diameter sufficient to engage the side wall of the cavity into
which the balls 60 and 61 extend, portions of the balls 60 and 61
will be held in the groove 62, by the tube which will resist
movement of the plunger 54. If the tube has an outer diameter
sufficient to hold portions of the balls 60 and 61 in the groove 62
and if the inner diameter of the tube is such as to cause the tube
to grip the pin 56, then, movement of the plunger 54 by the tube
will be resisted.
FIGS. 6a and 7a show a lock generally similar to that of FIGS. 6
and 7, but equipped with an extra set of locking balls 60a and 61a
spaced from the locking balls 60 and 61. These additional locking
balls function similarly to the additional locking balls of the
embodiments of FIGS. 3A-3C in that they require a key to have an
arcuate recess properly located to receive the locking balls 60a
and 61a to prevent the radially outward movement of the locking
balls into the peripheral groove 62a. FIG. 6A shows the operation
of a correct key 163 which is similar to the key 63 except for the
fact that the key 163 has a circumferential recess R which is
opposed to the groove 62a when the key 163 is in its unlocking
position.
The improper key 164 shown in FIG. 7A cannot unlock the mechanism
of FIGS. 6A and 7A. Not only does the key 164 have a spacing
between the abutment and finger ends, like the key 64 of FIG. 7,
but also, the key 164 has no circumferential recess R to allow
inward movement of the locking balls 60a and 61a.
The lock 46a illustrated in FIGS. 8 and 9 contains both a modified
plunger 65 and a modified pin 66, the balls 60 and 61 being
restrained or released dependent upon the position of the pin 66.
The pin 66 has a peripheral groove 67 which, when the pin 66 is in
its normal position shown in FIG. 8, permits the balls 60 and 61 to
move out of the groove 62. However, when the pin 66 is moved to the
left, as shown in FIG. 9, the outer surface of the pin 66 prevents
the balls 60 and 61 from moving out of the groove 62. Accordingly,
if an attempt is made to open the lock 46a with an implement which
holds the pin 66 in the position shown in FIG. 9, movement of the
plunger 65 from its locking position to its unlocking position will
be prevented. Also, if a rod, such as the rod 68 shown in FIG. 9 is
inserted in the lock 46a and is driven against the pin 66 with
sufficient force to bend the pin 66 or to deform it, such as at 69,
by an amount which will cause the pin 66 to remain in the position
shown in FIG. 9, then, the plunger 65 cannot thereafter be moved
toward its unlocking position even by a correct key, the latter
indicating tampering with the lock 46a.
FIG. 10 shows how any and all of the locking balls in the various
embodiments of the mechanism of the invention can be kept from
falling out of the axially inner ends of their respective
passageways and/or grooves. The locking ball B of FIG. 10 can be
taken to represent any of the locking balls previously discussed,
and the passageway P in which the ball B is lodged for inward and
outward movement represents any of the passageways in which the
locking balls have been shown. It will be seen that although the
passageway P has a slightly larger diameter than the ball B for
free to and fro motion of the ball, the open end, or mouth M of the
passageway P is of a smaller diameter than the ball B. Thus the
ball B may protrude from the passageway mouth M but cannot fall out
of the passageway P. To form a passageway one can simply drill the
passageway P and stop drilling before the drill has passed
completely through the surrounding material, leaving a lip at the
mouth of the passageway.
FIG. 11 illustrates another modification of a plunger type lock of
the type illustrated in U.S. Pat. No. 4,040,279 and briefly
described above in connection with FIGS. 4 and 5. In a lock of this
type a plunger socket is engageable by outwardly expandable fingers
of a key (not shown in FIG. 11).
The socket 138 of FIG. 11, like the socket 38 of FIG. 4, has
locking balls 141 and 142 received in passageways 143 and 144. A
portion 145 of the socket wall, through which the passageways 143
and 144 extend tapers outwardly toward the open end of the socket
138. Inwardly of the tapered, or frusto-conical wall portion 145,
the socket wall is cylindrical, as shown at 146.
It will be understood that an authorized key will be so dimensioned
for use in conjunction with a socket of the type shown in FIG. 11
that the key fingers will engage the cylindrical wall portion 146
of the socket, to the rear of the locking balls 141, 142, to open
the lock, which otherwise operates like the lock of FIGS. 4 and 5.
An attempt to open a lock fitted with a socketed plunger according
to FIG. 11 with an unauthorized key will result in failure of the
key to engage the tapered portion 145 of the socket wall, or will
cause the locking balls 141, 142 to move outward into grooves and
thus prevent unlocking.
FIG. 12 is similar to FIG. 3 in showing an arrangement of locking
balls arranged in a socket's wall, except that three such balls
119, 120 and 121 are shown mounted at angles of 120 degrees with
respect to each other about the axis of the figure. The use of
three balls rather than two as in FIG. 2 assures that at least one
of the balls 119, 120 or 121 will be driven outward to engage a
matching groove if a foreign object such as an unauthorized key is
inserted into the lock. The arrangement of FIG. 12 can be employed
whether or not the socket has a tapered inner wall.
FIGS. 13 and 14 show a key 125 and socket 124 for more positive
engagement. As in the embodiment of FIG. 5, the key 125 of FIG. 4
has fingers 126 separated by grooves 127 so that the fingers 126
can be expanded radially outward for engagement with the socket
wall 130 by means such as those fully described in U.S. Pat. No.
4,040,279, the disclosure of which is hereby incorporated by
reference.
Unlike the key and socket of said patent, the key of FIG. 14 and
socket of FIG. 13 are provided with mating projections 128 on the
key fingers 126 and a recess 131 in the socket wall 130, which wall
130 is tapered as previously described.
When a key 125 of the proper length is extended into the socket of
FIG. 13 the projections 128 will fit into the mating recess 131
upon the expansion outward of the fingers 126 by the wedging action
of the tip 129 of the key's central rod. The locking balls and
locking ball receiving groove shown in FIGS. 13 and 14 function as
already described.
Although preferred embodiments of the present invention have been
described and illustrated, it will be apparent to those skilled in
the art that various modifications may be made without departing
from the principles of the invention.
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